There is currently a demand for pneumatic tires to be improved in various performance areas. Such improvement may be realized through the design of tread patterns. Heavy duty tires have been provided with a tread pattern designed with improved traction performance in mind.
For example, a heavy duty pneumatic tire is known which improves both traction characteristics on bad roads until the terminal stage of wear and wet performance at high-speeds in a compatible manner (see Japanese Unexamined Patent Application Publication No. H09-136514A). This heavy duty pneumatic tire includes a tread provided with at least one circumferential main groove extending in the circumferential direction, and a plurality of lateral grooves disposed on opposite sides of the circumferential main groove at intervals in the circumferential direction. The plurality of lateral grooves are connected to the circumferential main groove. The circumferential main groove extend in the circumferential direction in a tread central region that corresponds to 50% of the ground contact width. The groove depth of the circumferential main groove is 5% or greater of the ground contact width. The lateral grooves provided in at least the regions on opposite sides of the tread have a groove depth 109% or greater the groove depth of the circumferential main groove.
In this heavy duty pneumatic tire, the area of the tread center region is made large so as to increase the cut resistance performance and wear resistance performance. However, a large tread center region land portion area leads to an increase in the amount of heat build-up, and a small groove area leads to the amount of heat dissipated decreasing. As a result, heat build-up resistance is reduced. Also, increasing the groove area to increase heat build-up resistance results in stones becoming more likely to lodge in the grooves.